Numerical investigation on flow and heat transfer characteristics of helium-xenon gas mixture in rod bundles

The helium-xenon(He-Xe) gas mixture with low Prandtl number and good heat transfer characteristics suits for the advanced high heat flux and compact gas-cooled reactors. A numerical simulation was conducted on the flow, heat transfer, and turbulent mixing characteristics of He-Xe gas mixture in a tightly arranged triangular rod bundle subchannel. The transition characteristics of He-Xe gas mixture in rod bundle structure were obtained. The friction resistance coefficient, Nusselt number(Nu), and turbulent mixing factor beta was corrected within the Reynolds number(Re) range of 3 x 102 -1.8 x 105. The research results indicate that the transition occurs at Re equal to 2000 and forms a transition zone within the Re range of 2000-5000; The Blasius correlation can describe the wholly turbulent flow precisely, but it is suitable to adopt a new formula in the transition zone; The local Nu prediction performance of the modified Peckett correlation is in good agreement with the numerical simulation results, and the Petukhov correlation with shape correction and temperature correction factors has good pre-diction results on global Nu; The turbulent mixing factor using Re and shape parameters can better describe the mixing characteristics. This study has reference value for the design of rod bundle reactors using He-Xe gas mixtures as working fluids.